This program is concerned with the development of more precise and detailed knowledge of the transducer properties and color vision in the retinula and monopolar cells of the Diptera insects. The necessary general background of their nervous systems and a series of newly developed experimental and analysis techniques have now been developed that make this feasible. The new experimental techniques include the ability to perform the first reliable intracellular experiments, stable for long durations, ranging from all the many mutants of Drosophila (the fruit fly) through all of the Diptera and the honeybee. In addition to the recording of generator potentials, accurately controlled current, calcium and sodium injections can be made. Internal staining for extensive new correlations to the physiology by electronic microscopy is perfected. The important analytical procedures based upon nonlinear identification theory enable the verification of long-time preparation stability. The also enable the precise determination of the functional properties for combinations of light and injection stimuli at a known well-defined adaptation state. That is to say, they permit the definition of functional properties as a function of color-adaptation, polarization etc., before a change has occurred due to the stimulus.